The present invention relates to a heavy vehicle chassis configuration and more particularly to a cost-effective and efficient mid-engine chassis powertrain configuration suitable for use in a fire truck.
Fire trucks are often considered xe2x80x9cheavyxe2x80x9d vehicles typically referring to their weight of more than 10,000 pounds. These vehicles usually have an engine mounted forward of the front axle or front suspension. A heavy vehicle chassis typically houses mechanical workings such as suspension, powertrain, steering, braking, and cooling systems. Overall vehicle construction typically includes a chassis, a superstructure, and a cab (or body). See generally, U.S. Pat. No. 5,863,070 to Williams, et al., and U.S. Pat. No. 5,314,205 to Glesmann.
Heavy vehicles, not surprisingly, often require heavy engines to propel them. Front and rear mounted engines can create a vehicle with uneven weight distribution. Front-end engine placement (i.e., mounted ahead of a front axle or front suspension) creates a large engine housing that extends into the vehicle cab and subjects occupants to excessive engine heat and noise. This housing often covers part of an engine tunnel (or channel) used to direct airflow past a heat exchanger. The tunnel and corresponding housing within the cab also significantly reduce driver and passenger space in the front of the vehicle. Nevertheless, a vehicle designer is forced to restrict space in the vehicle cab to accommodate the engine housing and tunnel.
Rear-end engine placement configurations in trucks (i.e., engine is mounted behind the rear axle) are known in the art as a way to reduce engine noise, space and heat in the vehicle cab as described above. See generally, U.S. Pat. No. 4,811,804 to Ewers et al. This design achieves these goals but at great expense and loss of much of the rearward usable chassis space.
Mid-engine truck chassis configurations are also known in the art including fire trucks. For example, U.S. Pat. No. 4,059,170 to Young claims a mid-engine chassis design as a means to improve vehicle handling and safety by significantly reducing the load to the front tires. Mid-engine placement in a heavy fire truck chassis has been referred to in the art as a Spartan Motor Baron-type configuration. The mid-engine configuration allows more design flexibility and conveniences but is expensive since specialized and complicated cooling systems need to be adapted for such a configuration.
Thus, there is a desire and need for a heavy vehicle chassis that not only improves vehicle cab occupancy space, weight distribution, handling, and design flexibility, but also accomplishes these objects in a manner that is cost-effective and efficient.
Accordingly, the present invention provides a truck chassis configuration. Overall, engine placement in the chassis configuration of the present invention allows sufficient ground clearance, reduces overall engine noise within the cab, provides easy access for maintenance, improves handling and maneuverability, and simplifies engine cooling systems. The engine placement is also cost-effective, while not raising the vehicle""s overall center of gravity or significantly increasing vehicle cost.
The invention is a truck with a chassis frame having at least two chassis frame rails having a forward region and a rearward region, at least one intermediate cross member connecting the frame rails, a forward wheel assembly comprising at least two front wheels, a forward axle, and a forward suspension assembly attached to the chassis frame rails, and a rearward wheel assembly comprising at least two rearward wheels, at least one rearward axle, and rearward suspension assembly attached to the chassis frame rails. The invention is a truck with a powertrain comprising an engine, transmission and drive-shaft mounted to at least one wheel assembly positioned between and attached to the chassis frame rails between the front wheel assembly and the rearward wheel assembly and being at a position that the engine top extends no more than 10 percent of an overall engine height above the chassis frame rails.
The invention can have a engine or powertrain cooling system disposed between the chassis frame rails that can have a heat exchanger, a fan (mechanical or hydrostatic), an engine tunnel configured to extend no more than 24 inches (61 cm) in height above the chassis frame rail at its highest point and extending above the chassis frame rails no more than 38 inches (97 cm) in length, the engine tunnel width defined by a dimension separating the chassis frame rails, and a coolant flow path connecting the engine and the heat exchanger. The heat exchanger can be located at the front or rear of the engine tunnel or anywhere in between.
In one embodiment of the present invention, the heat exchanger can be non-vertical, including horizontal. In this embodiment, the need for an engine tunnel is significantly reduced or even eliminated.
The present invention can also have a cab attached to and above a forward region of the chassis frame comprising a cab floor and a cab floor inclined front section, the cab floor inclined front section configured to conform to the dimensions of the engine tunnel.
Other objects of the present invention will become more apparent to persons having ordinary skill in the art to which the present invention pertains from the following description taken in conjunction with the accompanying figures.